Subtitles of the Movie

We now understand that a Parent Group has an additional Blend Mode called Pass Through and we understand that Pass Through make Motion calculate its compositing and Blend Modes as if all the objects of all the groups were in one big stack. In the science of compositing this is called concatenation. In other words, Motion does not finish calculating what your scene looks like until every object in your scene is entered into the calculation. So if you think of each group being its own calculation what Motion does is combine the values of every group or subcalculation into one very big calculation. In other words, every object can affect the appearance of every other object in your scene. Now you won't run into the term concatenation in the Motion manual, but you will run into the term Rasterization. Rasterization is the inverse of concatenation. Rasterization says, no, every group is its own little universe, its own calculation which results in an image. Now you may have these images stacked on top of each other like a bunch of Polaroids, but they're essentially separate. So, now I'm about to introduce to you how and when Motion rasterizes. Back to a simple scene here with our gears in one group and our Checkerboard in a Background group and our top group, Profile Group, has the profile of the woman in it, but let's start off with the Gears Group. All of the gears have their Blend Modes set to Add and because we see their color values brightened against the Checkerboard we know without looking that their Parent Group has a Pass Through Blend Mode. OK, you can look. Yup. Pass Through. Now, as soon as I change that Blend Mode from Pass Through to Normal, a few things happen. One, the gears mix by adding their colors against each other only; two, a little LED light pops on next to the Blend Mode. This is called the Rasterization Indicator. I'm going to call it the LED from now on because it's just easier to say. And three, around the Parent Group's Icon is now a box. Now you may not see an LED appear every time Rasterization occurs, but you will see a box around a group that's been rasterized. The LED pops on just to show what caused the rasterization if it can be identified in the Inspector tab. Let's show the HUD. It doesn't appear in the HUD, so we'll close that. OK, so that make sense so far. We expected that, right? We already knew that a Normal Blend Mode for a group makes Motion treat that group, for all practical purposes, as one layer. Let's turn off the Gear Group and we'll turn on the Profile Group with our lady in profile. I'm going to pick the woman object and set its Blend Mode to Add. So far so good. We see her mix with the Checkerboard Background group, just like the gears did. Now, let's check her profile Parent Group. Yes, Pass Through. Back to the woman layer and I'll enable Drop Shadow and we have a big red drop shadow and her Add Blend Mode mixes with the red, but the red doesn't mix with the Background because Motion doesn't calculate the shadow with the object. So, the shadow's color values are not added to the Checkerboard. If I change the Parent Group to Normal there's the LED. Then the woman only add mixes over her red shadow and not the Checkerboard on the left side of the frame. This is not the effect I want. I want both the woman and her shadow to mix additively with the Background, so back to the woman layer and now I'll set her Blend Mode to Normal, then back to the Parent layer and set its Blend Mode to Add and now I have the effect I want. And then we still have the LED. In fact, I'll try another Blend Mode and another and another and we still have the LED. So, every Blend Mode for the Parent Group causes Rasterization, but in this case, that's exactly what I want. I want the Profile Group with the woman and her shadow all to be treated as one object. Let's turn that group off and back to the Gear Group which has more than one object. Let's say I want these bright gears that their Blend Modes give me, but this time I want normal drop shadows. Now because there are so many gears my first thought would be to just give their parent group a drop shadow instead of going into each and every gear object and turning on their drop shadows. So, let's do that and select the parent group and Enable Drop Shadow. Well, I got what I wanted with every gear getting a shadow, but I lost my Add Blend Mode and there's that LED staring at me. But, this time it's next to the Drop Shadow Parameter, which means the group's Drop Shadow caused the Rasterization and in the Layer tab we now have a box around the gear group. OK, rasterized again. So, I guess that means I have to enable every gear's drop shadow one by one, right? I only have four in this scene, but what if I had 100? That's a lot of clicking. OK, here's a tip. If you select all of your Layers you'll be able to edit them simultaneously in the Inspector. I have all my gears selected and in the Inspector just click once to Enable Drop Shadow and all of their drop shadows turn on. This works with other parameters as well, like Position and Opacity. I'm going to turn off their Drop Shadows now. OK, now Rasterization is also forced on by applying Filters to groups. Let's add a Blur to the gears. Now if I add it to the parent group I lose my Add Blend Mode again. The general rule of thumb, if you want to avoid Rasterization and use the Pass Through Blend Mode, which keeps the Add Blend Modes for the gears, is to apply a Filter to an object Layer instead. So, now I'll just copy the Blur Filter from the parent and I can go up to the Menu Bar and select Edit, Copy, or on the keyboard press Command-C and then I'll turn off the Blur from the parent group and then select all the gear object Layers and go back to the Menu Bar, Edit Menu and select Paste, or Command-V. And now the gears are all bright and blurred. It's kind of pretty like that. So, the key to understanding Rasterization, using it or avoiding it, is understanding what triggers it and choose when it makes more sense to apply an effect to a group or an object Layer and Rasterization occurs in 3D scenes as well but has a different effect, which we'll see later.